Automatic line testing apparatus, including means for indicating the type of trouble



May 1, 1951 F. KESSLER AUTOMATIC um: TESTING APPARATUS, INCLUDING MEANSFOR INDIC'ATING THE TYPE OF TROUBLE Filed Oct. 3, 1947 v 68 928 EN:

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INVEN TOR. F rqnk Kass/er xOOOm J xoow flnm So XBN E 55 58 x25 xwmwni228200 mm EO Attorneys Patented May 1, 1 951 I AUTOMATIG LINE TESTINGAPPARATUS, INCLUDING MEANS FOR INDICATING THE TYPE OF TROUBLE FrankKessler, Rochester, N. Y., assignor to Automatic Electric Laboratories,llnc., Chicago,

111., a corporation of Delaware Application October 3, 1947, Serial No.777,663

Claims.

The present invention relates to automatic line testing apparatus andmore particularly to such apparatus that is especially adapted for usein conjunction with a test board incorporated in a switching testingtelephone system of the character of that disclosed in the copendingapplication of Frank Kessler, Serial No. 774,495, filed September 17,1947.

. In this switching testing telephone system, a test board of the manualdial and key controlled type is provided that has access via anautomatic testing switch train to subscriber lines, whereby the operatorat the test board may controlthe associated testing switch train toselect any one of the subscriber lines to be tested. Thereafter theoperator at the test board may perform a great number of individual keyoperations in order to cause the associated position testing equipmentto perform a corresponding number of individual tests upon the connectedsubscriber line; whereby the different types of faults upon theconnected subscriber line may be detected and measured.

While this testing facility is very flexible per-.

mitting the detection of each individual type of fault, as well as aprecise measurement of the severity or intensity thereof, a number ofkey operations on the part of the operator at the test board arerequired and more time is consumed in performing a routine test than isdesirable.

Accordingly, it is a general object of the present invention to provideautomatic line testing apparatus that is especially adapted for use inconjunction with a test board of the character described, whichapparatus is operative extremely fast to perform a routine test and todetect a line fault and to classify the type thereof, whereby it isnecessary for the operator at the test board to perform the keycontrolled precision tests mentioned only in the event the automaticline testing apparatus has indicated the presence and type of a linefault on the connected subscriber line.

Another object of the invention is to provide automatic line testingapparatus of improved circuit connection and arrangement.

7 A further object of the invention is to provide automatic'line testingapparatus that is capable of performing in sequence in a rapid andreliable manner, a number of tests for the more common types oflinefaults.

3 Further features of the invention pertain to the particulararrangement of the circuit eleme'ntsv of the system, whereby theabove-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the accompanying drawing in which the single figure is aschematic diagram of a telephone system embodying the present inventionand illustrating the general arrangement of the apparatus incorporatedin the exchange thereof, as well as the details of an automatic linetesting circuit provided therein.

Referring now more particularly to the drawing, the telephone systemthere illustrated comprises an exchange of the automatic type, includinga number of subscriber substations, one of which is indicated at TX, thesubscriber substation TX being provided with a subscriber line if: IXextending thereto and having a line circuit iiElX individuallyassociated therewith. Also the exchange comprises automatic switchingapparatus, not shown, including finders, selectors, and connectors thatare utilized for the purpose of setting up connections to and from thesubscriber substations therein.

Further, the exchange comprises a test board 2038K and a test switchtrain including a test diatributor trunk circuit lilllX, a connectedtest distributor switch 2960 and a pluralityof test connector switches,including the test connector switch 2 iEioX having access to the groupof subscriber lines, including the subscriber line 40|X extendingFinally, the exchange comprises an automatic line testing circuit lllilprovided with a relay group including a test relay RI ill, a start relayHi It, a step relay am, a pick-up relay Rl25, a battery relay R530, aground relay R140, a loop relay R155, and a stop relay RIM. Associatedwith and connected to the automatic line testing circuit Ito are abattery lamp LIEIZ, a ground lamp L193, and a loop lamp LIM, as well asan adjustable resistor Hi5 and a sequence test key KIM all disposed atthe test board 209K.

In the telephone system, the pieces of appa-- ratus identified by thenotation X correspond to the same elements, without the notation,disclosed in the telephone system of the previously mentioned Kesslerapplication. I Specifically, the test board EEEIX corresponds to thetest board 200 disclosed in detail in Figs. 2 and 8 to 19, inclusive,

of the Kessler application mentioned; the test distributor trunk circuitlilGX corresponds to the test distributor trunk circuit disclosed in tothe subscriber substation TX;

detail in Fig. 7 of the Kessler application mentioned; the testdistributor switch 2600K corre-- sponds to the test distributor switch2300 disclosed in detail in Fig. of the Kessler application mentioned;and the test connector switch 2 IBOX corresponds to the test connectorswitch 2I00 disclosed in detail in Fig. 21 of the Kessler applicationmentioned.

A better understanding of the connection and arrangement of theapparatus incorporated in the telephone system will be facilitated froma consideration of the operation of the automatic line testing circuitI06 to perform sequence line tests upon the subscriber line iiilXextending to the subscriber substation TX.

As disclosed in the Kessler application mentioned, the test board 2862icomprises position testing equipment terminating the conductors C254X,C255X, C251X and C25|X extending to the test distributor trunk circuitIBEX; and in the present arrangement the line conductors C254X and 0255Khave been terminated on the blades of the sequence test key Kid! wherebythey are connected via the second and third contacts of the sequencetest key KIBI when the sequence test key Kill! occupies its restoredposition, directly into the position testing equipment. Accordingly, theoperator at the test board ZGGX may perform a key operation thereat inorder to cause the condutcors 0254K, 0255K, C257X and C25IX extending tothe test distributor trunk circuit HIBX to be seized; whereby the testdistributor trunk circuit TGL X is seized effecting seizure of the testdistributor switch 2900K. The operator at the test board ZOUX thenoperates the dial in the associated position testing equipment inaccordance with four predetermined digits comprising the directorynumber of the called subscriber substation TX. The test distributorswitch 2900K responds to the first and second of the digits mentioned toselect the corresponding test connector switch 2160K; whereby the idleor busy condition thereof is tested in the test distributor switch2860K. Assuming that the test connector switch 2208K is idle at thistime, the test distributor switch 2009K seizes it; whereby the testconnector switch ZEQGX is rendered responsive to the third and fourthdigits dialed at the test board 209K. More particularly, the testconnector 2 l 00X responds to the third and fourth digits mentioned toselect the subscriber line IX extending to the called subscribersubstation TX; whereby the test connector switch 2| 60X tests the idleor busy condition thereof. Assuming. that the subscriber substation TXis idle at this time, the test connector switch 2 I 00X switches throughcompleting a direct metallic test circuit between the line conductors ofthe subscriber line MIX extending to the called subscriber substation TXand the line conductors 0254K and C2 X terminated in the positiontesting equipment at the test board 209K via the test distributor trunkcircuit 10671, the test distributor switch ZBUBX and the test connectorswitch 2IBGX. At this time the operator at the test board 288K mayselectively perform any one of-agreat number of individual keyoperations in order to cause the associated position testing equipmentto test the subscriber line diHX for corresponding faults and circuitconditions thereon. Specifically, at this time, by performing theappropriate individual key operations, the operator at the test board280K may cause the associated'position testing equipment to test thesubscriber-line MIX extending to the called subscriber substation TX forinsulation faults, in cluding insulation faults to battery potentialthereon, insulation faults to ground potential thereon and insulationloop faults between the line conductors thereof.

While the position testing equipment associated with the test board ZGUXis extremely flexible, permitting a great number of individual testswith respect to the subscriber line seix, as

well as with respect to the individual line conductors thereof, the keyoperations required are correspondingly rather numerous and somewhattime consuming. Accordingly, the operator at the test board 200K afterextending a test connection from the associated position testingequipment to the subscriber line GEHX, as noted above, may wish toperform automatically a number of insulation tests thereon withoutcarrying out the individual key operations previously noted. In order toaccomplish this end, the operator at the test board ZGUX after settingup the test connection between the associated position testing equipmentand the subscriber line iHX, as noted above, merely operates thenon-locking sequence test key KIM; whereby there is interrupted, at thesecond and third contacts thereof, the normal connection between theassociated position testing equipment and the line conductors C2 54X andC255X extending directly via metallic paths to the line conductors ofthe subscriber line d8 i X. Also at the first and fourth contacts of thesequence test key KIM, the line conductors GEE-1X and C255X are directlyconnected to the automatic line testing circuit I00. Finally, at thefifth contacts of the sequence test key Klfll there is completed acircuit for operating the start relay Rl|5 in the automatic line testingcircuit I86. Upon operating the start relay RI i5 initiates a cycle ofoperation of the automatic line testing circuit I00; whereby sequentialinsulation tests are performed therein upon the subscriber line MHX forfaults to battery potential thereon, faults to ground potential thereonand loop faults across the line conductors thereof.

More particularly, upon operating the start relay RI I 5 compietes, atthe contacts I it and I IT, a circuit, including the contacts 16! andIII, for operating the step relay RIZQ. Upon operating the step relayRIZD completes, at the contacts l2|., a circuit for operating thepick-up relay EH25; and completes, at the contacts I22, a circuit,including the contacts Hi l, for energizing the lower winding of thebattery relay R|30 in order to cause the'latter relay to operate throughits first step, the latter relay being of the twostep type. When thebattery relay RISO operates through its first ste it completes, at thecontacts ['32, a path, including the contacts H6, ltl, 134 and I 22, forshort-circuiting the upper Winding thereof, thereby positively toprevent the latter relay from operating through its second step at thistime. Upon operating the pick-up relay R completes, at the contacts 23and E27 a pick-up circuit, including the resistor H8 for operating thetest relay R1 Iii. Upon operating the test relay RIM] interrupts, at thecontacts HI, the circuit for retaining operated the step relay Ri20.Upon restoring the step relay RIZU interrupts, at the contacts I22, thepreviously traced path for short-circuiting the upper winding of thebattery relay R; whereby a circuit, including the contacts H6, 16!, and132 is completed for energizing in series the upper and lower windingsof the battery relay 'RISH in order 75 toc'ause the latter relay tooperate through its S 'secondistep. When the battery relay RI3G operatesthrough its second step, it interrupts, at the contacts I34, a furtherpoint in the circuit for energizing the lower winding thereof; prepares,at the contacts I33, a point in a circuit traced hereinafter forenergizing the lower winding of the ground relay RIM; and completes, atthe contacts I3I, a circuit, including the contacts I5I and MI, forilluminating the battery lamp LI02 at. the test board ZKIUX in order toindicate to the operator thereat that an insulation fault to batterypotential test is being performed by the automatic line testing circuitIilll upon the connected subscriber line MIX.

Also the battery relay Rite completes, at the contacts I 35 and I36, abridge connection, in cluding the contacts I51 and the first and fourthcontacts of the sequence test key KI I, to the line conductors C254X and0255K. Also the battery relay RI30 completes, at the contacts I31, atest path, including the contacts M9, for applying ground potential tothe bank of the adjustable resistor I and consequently through theindividual resistors Ifila, IIIlb, etc., to the rotatable arm I06 andthence through the resistor I08 to the left-hand terminal of the windingof the test relay RI II)"; which test path is extended through thewindings of the test relay RI I0 via the contacts I41 to the contactsI35 and I36 included in the above traced bridge connection extending tothe line conductors CZMX and C255X and consequently to the lineconductors of the subscriber line 40 IX. Accordingly, at this time, inthe event an insulation fault to battery potential is present uponeither of the line conductors of the sub-- scriber line 48IX, thepresence of battery potential thereon completes the above traced circuitvia the bridge connection and the test path for energizing the windingsof the test relay RI I0.

Of course, in the event no insulation fault to battery'potential ispresent upon either of the line conductors of the subscriber line All IXthe above traced circuit for energizing the windings of the test relayRI I0 is not completed.

Also upon restoring the step relay RIZIJ interrupts, at the contactsIZI, the circuit for retaining operated the pick-up relay RIZ5. Uponrestoring the pick-up relay RI25 interrupts, at the contacts I26 andI21, the pick-up circuit for energizing the winding of the test relay RII0. Accordingly, at this time the test relay RI It is retained in itsoperated position in the event an insulation fault to battery potentialappears upon the subscriber line IIEIIX; and is restored in the event noinsulation fault to battery potential appears upon the subscriber lineIOIX as explainedabove. First assuming that an insulation faulttobattery potential appears upon the subscriber line MIX, the test relayRI I0 is retained in its operated position preventing further operationof the step relay RIZEJ; whereby the operated battery relay l'tliillretains illuminated the battery lamp LIIJZ at the test board ZililX.Accordingly, further operation of the automatic line testing circuitIt!!! is arrested and the illuminated battery lamp LIOZ indicates to theoperator at the test board 2510K that the automatic line testing circuitI60 has tested the subscriber line 48 IX as having an insulation faultto battery potential thereon. At this .time the operator at the testboard 200K may restore the sequence test key KIIII, thereby to releasethe automatic line testing circuit IIiIl as explainedmore fullyhereinafter-and to'causethe line conductors C254X V and,.C 255X again tobe connected at the second Now assuming that no insulation fault tobat-- restoration of the pick-up relay Rl25; and recompletes, at thecontacts III, the circuit for operating the step relay RIZEI; wherebythe latter relay upon operating, completes, at the contacts IZI, thecircuit for operating the pick-up relay RI25. Also the step relay R120completes, at the contacts I22, the previously mentioned circuit,including the contacts I33 and I45, for ener-' gizing the lower windingof the ground relay RI 40 in order to cause the latter relay to operatethrough its first step, it being of the two-step type. When the groundrelay Rlt "operates, through its -first step, it completes, at thecontacts I43, a path, including the contacts I I6, I6I, I45, I33 andI22, for short-circuiting the upper winding thereof, thereby positivelyto prevent the latter relay from operating through its second step atthis time. Upon operating, the pick-up relay RI25 completes, at thecontacts I26 and I21, the pick-up circuit for operating the test relayRIIG. Upon operating the test relay RI Ill interrupts, at the contacts II I, the circuit for retaining operated the step relay RIM. Uponrestoring, the step relay RIZii interrupts, at the contacts, I22, thepreviously traced path for shortcircuiting the upper winding of theground relay RIM); whereby a circuit, including the contacts H6, IfiIand M3, is completed for energizing in series the upper and lowerwindings of the ground relay RIM] in order to cause the latter relay tooperate through its second step. When the ground relay Ridd operatesthrough its second step, it interrupts, at the contacts 245, a furtherpoint in the circuit for energizing the lower Winding thereof; prepares,at the contacts I44, a point in a circuit traced hereinafter forenergizing the lower winding of the loop relay RISE]; interrupts, at thecontacts I4I, the circuit for illuminating the battery lamp LIUZ at thetest board 200K; and completes, at the contacts I42, a circuit,including the contacts IEI, for illuminating the ground lamp Li &3 atthe test board 200)! in order to indicate to the operator thereat thatan insu lation fault to ground potential is being performed by theautomatic line testing circuit I99 upon the connected subscriber lineIOIX.

Also the ground relay RIM) interrupts, at the contacts M7, thepreviously traced connection between the bridge connection and theright-' hand terminal of thetest relayRI Iii; and com-, pletes, at thecontacts I66, a test path between the resistor H8 and the right-handterminal of the test relay RI I0, the resistor H8 being connected tobattery potential as previously noted.- Furtherthe ground relay RIM!interrupts, at the contacts I49, the previously traced path for ap-.

I and through the individual resistors LIEla,

Illllb, etc., and the contacts I48 to the contacts I36 and I 35 includedin the previously traced bridge connection. Hence, the battery potentialmentioned is extended via contacts I51 and the first and fourth contactsof the sequence test key KIBI to the line conductors 0254K and C255X andconsequently to the line conductors of the subscriber line iiHX.Accordingly, at this time, in the event an insulation fault to groundpotential is present upon either of the line conductors of thesubscriber line GQEX, the presence of ground potential thereon completesthe above traced circuit via the bridge connection and the test path forenergizing the windings of the test relay 'Ri Id. Of course, in theevent no insulation fault to ground potential is present upon either ofthe line conductors of the subscriber line 481K, the above tracedcircuit for energizing the windings of the test relay R! It is notcompleted.

Also upon restoring the step relay RIM interrupts, at the contacts I2I,the circuit for retaining operated the pick-up relay RI25. Uponrestoring the pick-up relay R525 interrupts, at the contacts I25 andI21, the pick-up circuit for energizing the winding of the test relay R!59. Accordingly, at this time the test relay RI H1 is retained in itsoperated position in the event an insulation fault to ground potentialappears upon the subscriber line Mix; and is restored in the event noinsulation fault to ground potential appears upon the subscriber lineMIX as explained above. First assuming that an insulation fault toground potential apears upon the subscriber line 40IX, the test relay REit is retained in its operated position preventing further operation ofthe step relay RIM; whereby the operated ground relay RI 4i retainsilluminated the ground lamp Llll3 at the test board ZtliX. Accordingiy,further operation of the automatic line testing circuit Iilfi isarrested and the illuminated ground lamp Lit-3 indicates to the operatorat the test board ZQEX that the automatic line testing circuit I90 hastested the subscriber line 43IX having an insulation fault to groundpotential thereon. At this time the operator at the test board 238K mayrestore the sequence test key KIBI, thereby to release the automaticline testing circuit IGG as explained more fully hereinafter and tocause the line conductors CZSQX and (325531 again to be connected at thesecond and third contacts of the sequence test key Klfii to theassociated. position testing equipment; whereby the associated positontesting equipment may be selectively operated in order to determine ingreater detail the characteristic of the insulation fault to groundpotential appearing upon the subscriber line 40IX.

Now assuming that no insulation fault to ground appears upon thesubscriber line .40IX, the test relay Ri'Itl is restored incident torestoration of the pick-up relay 'RI25; and recompletes, at the contactsIII, the circuit for operating the step relay RI2t; whereby the latterrelay upon operating completes, at the contacts I2I, the circuit foroperating the pick-up relay RI25. Also the step relay RI20 completes, atthe contacts I22, the previously mentioned circuit, including thecontacts I33, I44 and I55, for energizing the lower winding of the looprelay RIS!) in order to cause the latter relay to operate through itsfirst step, it being of the two-step type. When the loop relay 'RI 50operates through its first step, it completes, at the contacts I53,apath, including the contacts I16, IIiI, I55, I44, I33 :and I 22, forshort-acircuiting the 'upper'winding thereof, thereby positively toprevent the lat-'- ter relay from operating through its second step atthis time. Upon operating the pick-up relay RI25 completes, at thecontacts I26 and I21, the pick-up circuit for operating the test relayRI I0. Upon operating the test relay RIIB interrupts. at the contactsIII, the circuit for retaining operated the step relay RI 20. Uponrestoring the step relay Rm] interrupts, at the contacts I22, thepreviously traced path for short-circuiting the upper winding of theloop relay Rl50; whereby a circuit, including the contacts H6, I6I andI53, is completed for energizing in series the upper and lower windingsof the loop relay RI50 in order to cause the latter relay to operatethrough its second step. When the loop relay RI50 operates through itssecond step, it interrupts, at the contacts I55, a further point in thecircuit for energizing the lower winding thereof; prepares, at thecontacts I54, a point in a cir cuit traced hereinafter for energizingthe lower winding of the stop relay RIGO; interrupts, at the contactsII, the circuit for illuminating the ground lamp LI03 at the test board200K; and completes, at the contacts I52, a circuit for illuminating theloop lamp LI04 at the test board 260X in order to indicate to theoperator thereat that an insulation loop fault test is being performedby the automatic line testing circuit I upon the connected subscriberline 40IX.

Also the loop relay RI50 interrupts, at the contacts I51, the previouslytraced bridge connection between the line conductors C254X and (3255K;and completes, at the contacts 156, a direct path, including the firstcontacts of the sequence test key KIilI, fo applying ground potential tothe positive line conductor C254X. Also at this time, the previouslytraced test path, including the contacts I46, is completed for applyingbattery potential *by way of the resistor H8 to the right-hand windingof the test relay RIIil; which battery potential is extended via theresistor I98, the rotatable arm I06 of the adjustable resistor I05 andthrough the individual resistors IIl1a, 1012), etc., the contacts I48and the fourth contacts of the sequence test key K'IIlI to the negativeline conductor C255X. Accordingly, at this time, in the event aninsulation loop fault is present between the line conductors of thesubscriber line 40I X, there is completed the above traced circuit viathe test path ior energizing the windings of the test relay RI II). ofcourse, in the event no insulation loop fault is present between theline conductors of the subscriber line 40IX, the above traced circuitfor energizing the windings-0f the test relay RI I0 is not completed.

Also upon restoring the step relay Rl interrupts, at the contacts I2I,the circuit for retaining operated the pick-up relay RI25. Uponrestoring the pick-up relay Ri interrupts, at the contacts I26 and I21,the pick-up circuit for energizing the winding of the test relay RIIIl.Accordingly, at this time, the test relay RI I0 is retained in itsoperated position in the event an insulation loop fault appears upon thesubscriber line 4652;; and is restored in the event no insulation loopfault appears upon the subscriber line 405K as explained above. Firstassuming that an insulation loop fault appears upon the subscriber lineIX, the test relay RI I0 is retained in its operated position preventingfurther operation of the step relay RI20; whereby the operated looprelay RI retains illuminated the loop'lamp'LIM'at the testboard 200K.Accordingly, further operation of the automatic line testing circuit Iis arrested and the illuminated looplamp LI04 indicates to the operatorat the test board 200K that the automatic line testing circuit I00 hastested the subscriber line 40IX as having an insulation loop faultthereon. At this time the opeartor at the test board 200K may restorethe sequence test key KIOI, thereby to release the automatic linetesting circuit I00 as explained more fully hereinafter and to cause theline conductors C254X and C255X again to be connected at the second andthird contacts 'of the sequence test key KIIJI to the associatedposition testing equipment; whereby the associated position testingequipment may be selec tively operated in order to determine in greaterdetail the characteristic of the insulation loop fault appearing uponthe subscriber line 40IX.

10 tests upon the subscriber line 46 IX are performed by theautomaticline testing circuit I00. Accordingly, the battery lamp LI02, the groundlamp LI03, and the loop lamp LI04 are sequentially flashed momentarilyand then extinguished indicating that the automatic line testing circuitI00 has tested the subscriber line 40IX and has found thereon none ofthe insulation faults above described. Of course, in the event theautomatic line testing circuit I00 tests the subscriber line 60 IX ashaving one of the insulation faults thereof previously mentioned, thecorresponding lamp LI02, L403 or LI04 at the test board 200K isilluminated as previously explained, to identify the particularinsulation fault that has been found by the automatic line testingcircuit I00 to be upon the subscriber line 40IX all as previously Nowassuming that no insulation loop fault appears upon the subscriber line40IX, the test relay RI I0 is restoredincident to restoration of thepick-up relay RI25; and recompletes, at the contacts III, the circuitfor operating the step relay RI 20 ;v whereby the latter relay uponoperating completes, at the contacts I2 I, the circuit for operatingthepick-up relay RI25. Also the step relay RIZil completes, at thecontacts I22, the previously mentioned circuit, including the contactsI33, I44, I54 and I03, for energizing the lower winding of the stoprelay RI60 in order to cause the latter relay to operate through itsfirst step, it being of the two-step type. When the stop relay RI60operates through its first step, it completes, at the contacts I62, apath, including the contacts II6, I63, I54, I44, I33 and I22, forshort-circuiting the upper winding thereof, thereby positively toprevent the latter relay from operating through its second step at thistime. Upon operating the pick-up relay RI completes, at the contacts I26and I2! the pick-up circuit for operating the test relay RI I0. Uponoperating the test relay RI I0 interrupts, at the contacts III, thecircuit for retaining operated the step relay RI20. Upon restoring thestep relay RI20 interrupts, at the contacts I22, the previously tracedpath for short-circuiting the upper winding of the stop relay RI60;whereby there is completed, ,a circuit, including the contacts H6 andI62, for energizing in series the upper and lower windings of the stoprelay RI 60 causing the latter relay to operate through its second step,When the stop relay RI60 operates through its second step, itinterrupts, at the contacts I6I, the multiple holding circuits forenergizing in series the upper and lower windings of the battery relayR130, the ground relay RI and the loop relay RI in order to cause thelatter relays to restore. Upon restoring the loop relay RI 50interrupts, at the contacts I52, the circuit for illuminating the looplamp LI04 at the' test board 200K. Also the operated stop relay RI60prevents further operation of the step relay RIZO and the pick-up relayRI25; whereby the test relay RI I0 is retained in its restored positiontogether with the battery relay Ri30, the ground relay RI40 and the looprelay Rliifl. I v

In view of the foregoing, it will be understood that in the event theautomatic line testing circuit I00 tests the subscriber line 40IX ashaving thereon no insulation fault to battery potential, no insulationfault to ground potential and no insulation loop fault, the stop relayRI60 is operated a described above a brief time interval after thesequence test key KIOI is operated. Of course, in the meantime, thethree individual explained. I

Accordingly, when the operator at the test board 200X operates thesequential test key KI 0 I, the automatic line testing circuit I00 isoperated to perform the insulation fault tests above described and toindicate either no insulation'fault on the subscriber line 40 IX or theparticular insulation fault found thereon as described above. Theoperator at the toll board 200K then restores the sequence test key KIOIin order to interrupt, at the first and fourth contacts thereof, theconnection between the line conductors 02543! and C255X and theautomatic line testing circuit I00; and to complete, at the second andthird con tacts of the sequence test key KIIII, the connection betweenthe line conductors C2 54X and 025521 and the associated positiontesting equipment. Also when the sequence test key KIOI is restored,there is interrupted, at the fifth contacts thereof, the circuit forretaining operated the start relay RI I5 in the automatic line testingcircuit I00. Upon restoring the start relay RI I5 interrupts, at thecontacts I I6, the holding circuit for energizing in series the upperand lower windings of any operated one of the relays RI30, RIM, RI 50 orRI 60 at this time; whereby the automatic line testing circuit I00 iscompletely released and available for further use.

In conjunction with the operation of the automatic line testing circuitI00 to test the subscriber line 40 IX for the various insulation faultsthereon, previously described, it is noted that in each case, the testcircuit for retaining operated the test relay RI I0 in the automaticline testing circuit I00 includes the adjustable resistor I05 disposedat the test board 200K; whereby the operator at the test board ZIIBX mayselectively set the rotatable arm I06 of the adjustable resistor I05 inorder to include one or -more of the individual ressitors Iill'a, I0'Ib,etc., in the test circuit or to exclude all of the individual resistorsI01, etc., therefrom. This arrangement permits the operator at the testboard 200)! to estab lish the limits of the insulation fault testsperformed by the automatic line testing circuit I00 as it Will beappreciated that the test relay RI II] will be retained in its operatedposition to register the presence of a given insulation fault dependingboth upon the severity or intensity of the given insulation fault andthe adjustment of the adjustable resistor I05. In other words, the testrelay RI I0'is retained in its operated position to register a giveninsulaton fault only in the event the severity or intensity thereof isgreater than that for "which the adjustable resistor I65 is set by theoperator at the test board 200K. This ar-j rangement is veryadvantageous as it permits the operator'atthe test board 200K to-setreadily the 1 1 flexibility of operation of the automatic line testingcircuit [60 to register insulation faults.

In View of the foregoing it is apparent that there. has been provided anautomatic line testing circuit that may be employed in conjunction witha manual test board inorder to perform rapidly and in sequence aplurality of line insulation tests and to render to the operator at thetest board an appropriate signal indicating the results of the lineinsulation tests that are performed thereby.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such -m.odifications as fall within the truespirit and scope of the invention;

What is claimed is:

1.. In a telephone system including a test operator position, subscriberlines, a plurality of signals: disposed at said test operator positionand respectively corresponding to the types of faults that may occurupon a subscriber line, means controllable from said test operatorposition for setting up a test connection therefrom to any one of saidsubscriber lines, automatic testing appara tus, a start control, andadditional means controllable from said test operator position fortransferring said test connection to said one subscriber line from saidtest operator position to said apparatus and for transmitting said startcontrol to said apparatus; said apparatus comprising cyclic mechanismoperatively sequentially through a plurality of positions, meansresponsive to said start control for initiating operation of saidmechanism, a plurality of test circuits respec tively corresponding tothe positions of said mechanism and respectively corresponding to thetypes of faults that may occur. upon a subscriber line, a test device,means responsive to operation of said mechanism into its diiferentpositions for setting up corresponding ones of said test circuitsbetween said test device and said test connection and for selectingcorresponding ones of said signals, said test device being operated inresponse to the completion of any one of said test circuits so thatoperation of said test device when said mechanism occupies a given oneof its positions is indicative of the corresponding type of fault uponsaid one subscriber line, and means responsive to operation of said testdevice for arresting operation of said mechanism and for operating theselected one of said signals 2. In a telephone system including a testoperator position, subscriber lines, a plurality of signals disposed atsaid test operator position and respectivelycorresponding to the typesof faults that may occur upon a subscriber line, an adjustable selectordisposed at said test operator position, means controllable from saidtest operator position for setting up a test connection therefrom to anyone of said subscriber lines, automatic testing apparatus, a startcontrol, and additional means controllable from said test operatorposition for transfering said test connection to said one subscriberline from said test operator position via said selector to saidapparatus and for transmitting said start control to said apparatus;said apparatus comprising cyclic mechanism operatively sequentiallythrough aplurality of positions, means responsive to said start controlfor initiating operation of said mechanism, a plurality of test circuitsrespectively corresponding to the positions of said mechanism andrespectively corresponding to the types: of faults that may occur upon asubscriber line, a test device, means responsive to operation of saidmechanism into its difierent positions for setting up corresponding onesof said test cir cuits between said test device and said test connectionand for selecting corresponding ones of said signals, said test devicebeing operated in response to the completion of any one of said testcircuits so that operation of said test device when said mechanismoccupies a given one of its positions is indicative of the correspondingtype of fault upon said one subscriber line, said selector beingadjustable selectively to set the sensitivity of operation of said testdevice to a fault upon a subscriber line to which said test connectionis extended, and means responsive to operation of said test device forarresting operation of said mechanism and for operating the selected oneof said signals.

3. In a telephone system including a test operator position, subscriberlines, a plurality of signals disposed at said test operator positionand respectively corresponding to the types of faults that may occurupon a subscriber line, means controllable from said test operatorposition for setting up a test connection therefrom to any one of saidsubscriber lines, automatic testing apparatus, a start control, andadditional means controllable from said test operator position fortransferring said test connection to said one subscriber line from saidtest operator position to said apparatus and for transmitting said startcontrol to said apparatus; said apparatus comprising cyclic mechanismoperatively sequentially through a plurality of positions, meansresponsive tosaid start control for initiating operation of saidmechanism, a plurality of test circuits respectively corresponding tothe positions of saidmechanism and respectively corresponding to thetypes of faults that may occur upon a subscriber line, a test relay, apick-up circuit for operating said test relay, means responsive to saidstart control for completing said pick-up circuit, means responsive tooperation of said test relay for operating said mechanism into a firstof its positions, means responsive for operation of said mechanism intoits first position for setting up a first of said test circuits betweensaid test relay and said test connection and for operating thecorresponding first of said signals and for interrupting said pick-upcircuit so that said test relay is retained operated via said first testcircuit only in the event a corresponding first type of fault is presentupon said one subscriber line, means responsive to restoration of saidtest relay for recompleting said pick-up circuit, means responsive toreoperation of said test relay for operating said mechanism into a sec-0nd of its positions, means responsive to operation. of said mechanisminto its second position for setting up a second of said test circuitsbetween said test relay and said test connection and for restoring saidfirst signal and for operating the corresponding second of said signalsand for interrupting said pick-up circuit so that said test relay isretained operated via said second test circuit only in the event acorresponding second type of fault is present upon said one subscriberline, means responsive to restoration of said test relay forrecompleting said pick-up circuit, means responsive to reoperation ofsaid test relay for operating said mechanism into a third of itspositions, and means responsive to operation of said mechanism into itsthird position for restoring said second signal and for interruptingsaid pick-up circuit.

4. In a telephone system including a test operator position, subscriberlines, a plurality of signals disposed at said test operator positionand respectively corresponding to the types of faults that may occurupon a subscriber line, means controllable from said test operatorposition for setting up a test connection therefrom to any one of saidsubscriber lines, automatic testing apparatus, a start control, andadditional'means controllable from said test operator position fortransferring said test connection to said one subscriber line from saidtest operator position to said apparatus and for transmitting said startcontrol to said apparatus; said apparatus comprising cyclic mechanismoperatively sequentially through a plurality of positions, meansresponsive to said start control for initiating operation of saidmechanism, a plurality of test circuits respectively corresponding tothe positions of said mechanism and respectively corresponding to thetypes of faults that may occur upon a subscriber line, a test device,means responsive to operation of said mechanism into its differentpositions for setting up corresponding ones of said test circuitsbetween said test device and said test connection, said test devicebeing operated in response to the completion of any one of said testcircuits so that operation of said test device when said mechanismoccupies a given one of its positions is indicative of the correspondingtype of fault upon said one subscriber line, means responsive tooperation of said test device for arresting operation of said mechanism,and means for operating and for restoring sequentially said signals inresponse to operation of said mechanism through its different positionsin order to indicate that the corresponding tests have been made andthat the corresponding faults are not present upon said i one subscriberline, one of said signals corresponding to a given fault being retainedoperated in the event operation of said mechanism is arrested in acorresponding one of its positions.

5. In a telephone system including a test operator position, subscriberlines, each of said subscriber lines including a pair'of lineconductors, a plurality of signals disposed at said test operatorposition and respectively corresponding to the types of faults that mayoccur upon a subscriber line, means cont'rollable from said testoperator position for setting up a test connection therefrom to any oneof said subscriber lines, au-

tomatic testing apparatus, a start control, and additional meanscontrollable from said test operator position for transferring said testconnection to said one subscriber line from said test operator positionto said apparatus and for transmitting said start control to saidapparatus; said apparatus comprising cyclic mechanism operativelysequentially through a plurality of positions, means responsive to saidstart control for initiating operation of said mechanism, a testcircuit, a test device, battery and ground potentials, means responsiveto operation of said mechanism into a first of its positions forbridging together via said test connection the line conductors of saidone subscriber line and for setting up said test circuit thereto viasaid test device from said battery potential so that said test device isoperated in the event of a ground fault on either line conductor of saidone subscriber line, means responsive to operation of said mechanisminto a second of its positions for bridging together via said testconnection the line conductors of said one subscriber line and forsetting up said test circuit thereto via said test device from saidground potential so that said test device is operated in the event of abattery fault on either line conductor of said one subscriber line,means responsive to operation of said mechanism into a third of itspositions for setting up said test circuit to the line conductors ofsaid one subscriber line via said test device respectively from saidground potential and said battery potential so that said test device isoperated in the event of a loop fault between the line conductors ofsaid one subscriber line, additional means responsive to operation ofsaid mechanism into its different positions for selecting correspondingones of said signals, and means responsive to operation of said testrelay for arresting operation of said mechanism and for operating theselected one of said signals.

FRANK KESSLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,220,607 Clausen Mar. 2'7, 19171,340,935 Goodrum May 25, 1920 1,855,852 Freesland Apr. 26, 19321,881,544 Hartley Oct. 11, 1932 2,328,750 Smith et al. Sept. 7, 19432,329,491 Sulzer Sept. 14, 1943

